http://firmbuttexercises.com - The back hyperextension exercise works the back muscles and a little bit of glut muscles. Mostly lower back and a little bit of middle back muscles.

Video Transcription

Okay, so this exercise is called a back hyper extension or back extension. You lie flat on your stomach; you are basically focusing on all the muscles of the back, all the way up to the mid back and a little bit of a glute also, but mostly low back and a little bit of mid back. So I lie down, face down like this, and put my hands behind my neck. If this is a problem, if this hurts your neck at all, put your hands either like this or behind your back just like that. So I am going to put them just like this and the basic exercise is you lift your chest and your knees off the ground as far as you can. So just like that, you hold it for 1-1000 and you lie back. So it's just like this for a set of five. That's it.